Issue 119 Gardening

Companion planting strategies for vegetable gardens 

Companion planting is a gardening technique where certain plants are grown together to enhance growth, deter pests and improve overall garden health. This strategy leverages natural relationships between plants to create a thriving, balanced ecosystem. Below are effective companion planting strategies tailored for vegetable gardens, with a focus on pest control, soil improvement and space optimisation - principles that can be adapted to various climates, including Southeast Queensland’s subtropical conditions. 

Key benefits of companion planting 

• Pest control: Some plants repel harmful insects or attract beneficial ones that prey on pests. 

• Soil improvement: Certain plants enrich the soil with nutrients like nitrogen, benefiting neighbouring crops. 

• Space optimisation: Pairing tall and short plants or climbers and groundcovers maximises garden space. 

• Enhanced growth and flavor: Specific combinations may boost plant vigour or improve the taste of produce. 

Top companion plants and their roles 

Here are some widely used companion plants and their benefits, ideal for a vegetable garden: 

Marigolds (Tagetes spp.)   

Role: Repel nematodes, whiteflies and aphids; attract ladybugs and hoverflies (natural pest predators).   

Best paired with: Tomatoes, eggplants, leafy greens.   

Tip: Plant around garden edges or intersperse among veggies. 

Basil (Ocimum basilicum)  

Role: Repels whiteflies, mosquitoes and fruit flies; may enhance tomato flavour.   

Best paired with: Tomatoes, peppers.   

Tip: Its strong scent confuses pests, protecting nearby crops. 

Nasturtiums (Tropaeolum majus)   

Role: Acts as a ‘trap crop’ attracting aphids and caterpillars away from main crops.   

Best paired with: Cucumbers, zucchini, beans.   

Tip: Plant at garden borders to draw pests away. 

Garlic (Allium sativum) and Onions (Allium cepa)**   

Role: Deter aphids, slugs and fungal diseases; onions repel carrot fly.   

Best paired with: Carrots (onions), roses, fruit trees (garlic).   

Tip: Use as a natural pest barrier in rows or clusters. 

Legumes (Beans, Peas)   

Role: Fix nitrogen in the soil, enriching it for nearby plants.   

Best paired with: Corn, cucumbers, leafy greens.   

Tip: Rotate annually to maintain soil fertility. 

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Effective companion planting combinations 

These pairings have proven to work well in vegetable gardens: 

Tomatoes + Basil + Marigolds   

• Basil repels pests and boosts tomato flavour, while marigolds deter nematodes and attract beneficial insects.   

• Ideal for a productive summer bed. 

Carrots + Onions   

• Onions deter carrot fly and carrots aerate the soil for onions.   

• Perfect for raised beds or tight rows. 

Cucumbers + Nasturtiums   

• Nasturtiums attract aphids away from cucumbers and suppress weeds.   

• Great for sprawling garden layouts. 

Lettuce + Tall Plants (e.g. tomatoes or corn)   

• Taller plants provide shade for lettuce, protecting it from heat.   

• Useful in warm climates or seasons. 

Beans + Corn:   

• Corn acts as a trellis for climbing beans, while beans enrich the soil with nitrogen for corn.   

• A space-saving combo for small gardens. 

Plants to avoid pairing together 

Some plants compete for resources or attract similar pests, so keep these apart: 

Nightshades (tomatoes, potatoes, eggplants, peppers)   

As part of the same family, they share pests and diseases (e.g. blight, fruit fly).   

Solution: Separate with unrelated companions and rotate crops yearly. 

Beans + Onions/Garlic   

Onions and garlic can stunt legume growth.   

Solution: Plant in different garden sections. 

Cabbage + Strawberries   

Brassicas may inhibit strawberry development.   

Solution: Pair cabbage with dill or chamomile instead. 

Practical tips for success 

Use trap crops: Plant nasturtiums or mustard greens to lure pests away from valuable crops. Monitor and remove pests from these plants regularly. 

Rotate crops: Avoid planting the same plant families in the same spot each year to prevent soil depletion and pest buildup. 

Maximise vertical space: Use tall plants (e.g. sunflowers, corn) for shade or as supports for climbers (e.g. beans, peas) to save space and improve airflow. 

Monitor pests: In humid climates, watch for snails or fungal issues. Use garlic/onion sprays as natural deterrents and ensure good plant spacing. 

Building a thriving garden 

Companion planting is an easy, sustainable way to improve your vegetable garden’s health and yield. By pairing plants like marigolds with tomatoes or nasturtiums with cucumbers, you will reduce pest pressure and make the most of your space. Start with a few combinations, observe how they perform in your garden and adjust based on your local conditions. With time, you will cultivate a productive, resilient garden that works in harmony with nature. 

For further inspiration, explore local gardening resources or connect with community groups to share tips and seeds.  

Happy planting! 

Mole